In an oscillometric blood pressure measurement device as disclosed in Japanese Unexamined Patent Publication No. 2004-180910 (hereinafter referred to as Patent Document 1), a blood pressure of a measurer is measured by wrapping and fixing an armband (cuff) internally including an air bag to a predetermined site of a living body or the measurer, and measuring a change in internal pressure or a change from an initial state of the internal pressure by pressurizing and depressurizing the air bag.
FIG. 14 is a view describing a determination method of a blood pressure value in an oscillometric method. A portion (A) of FIG. 14 is a view showing a specific example of a change between a cuff pressure and an artery blood pressure and a relationship between the cuff pressure and the artery blood pressure involved with elapse of time with pressure on a vertical axis and time on a horizontal axis. In the portion (A) of FIG. 14, a curve A1 shows the change of the artery blood pressure, and a line segment (or curve) A2 shows the change of the cuff pressure. In this case, the cuff internal pressure is pressurized to a predetermined pressure at an initial stage, and then gradually depressurized at a constant depressurization speed in the next stage to perform blood pressure measurement in the depressurization stage. When determining the blood pressure value with reference to the portion (A) of FIG. 14, the measurement result from a time point (first time point) at which the cuff pressure corresponds to the maximum pressure (cardiac systolic blood pressure) of the artery blood pressure in the depressurization stage to a time point (second time point) at which the cuff pressure corresponds to the minimum pressure (cardiac diastolic blood pressure) of the artery blood pressure is used.
The portion (B) of FIG. 14 shows a curve (envelope curve) showing a change of an amplitude of the artery blood pressure wave with respect to the cuff pressure from the first time point to the second time point with a pressure pulse wave amplitude on a vertical axis and the cuff pressure on a horizontal axis. In the oscillometric method, the blood pressure value is determined using the envelope curve in the calculation.
In the conventional blood pressure measurement device as disclosed in Patent Document 1, the blood pressure is generally measured with clothes off or with sleeves rolled up. However, taking the clothes off or rolling up the sleeves in an area where the temperature is particularly low is a strong irritation to the body of the measurer, and becomes a cause of blood pressure fluctuation. Taking into consideration that the measurer who needs to have the blood pressure measured is often elderly, causing sudden irritation in the body of the measurer is preferably avoided as much as possible. In addition, an upper part of an upper arm is strongly compressed by rolling up the sleeves, to no small extent, and the influence on the blood pressure cannot be ignored. Thus, there is a demand to measure the blood pressure with clothes on. If the measurement can be carried out with the clothes on, the merit on the user side in that measurement can be more easily carried out is large.
Patent Document 1: Japanese Unexamined Patent Publication No. 2004-180910